Thanks Tummyrumbles......those are some things to think about.This sounds like a good theory:
"Having the same problem and looking at all the possible sources I have com to this conclusion. In the morning I have a regular bowel movement with no problems, however during the day there are the same issues with frequent semi watery movements with burning, itching sensation. Sometimes blood upon wiping. I believe that what is going on is that the digestive tract is passing along predigested food too quickly to the lower intestine. The normal digestive process takes some time and the end product is a succession of food that has gone through the stomach where it is broken down by strong acids, and onto the small and large intestines where the nutrients are absorbed until it reaches the end point. The pancreatic digestive compounds and bile from the liver are added early on to assist in breaking down the organic compounds but if the stool is passed quickly to the anus the acidic residue is still active an when passing to the sensitive rectal tissues , it burns and causes the issue described above. Sometimes the remedies of taking certain compounds probably neutralizes the effects or lines the digestive tract to the rectum so the acidic fluids are not exposed to the sensitive anal tissues. The fresh blood is from the irritation of the rectum after wiping and usually heals quickly."
I'd have a look at inflammatory foods. For some people, expecially with diarrhea, IBS could be a low level inflammatory bowel disorder. Wheat would be one of the biggest problem foods, but all of the high FODMAPs could also cause inflammation. Certain fats if you can't absorb them.
This site suggests: Inability of the rectum to stretch. If the muscles of the rectum are not as elastic as they should be, excess stool that builds up can leak out. Inflammatory bowel disease (such as Crohn's disease) can also affect the rectum's ability to stretch.
The best diet for everyone with IBS is a low inflammatory, mainly mild fibre diet that would be suitable for someone in a nursing home. Think bland and easy to digest. If you must eat wheat, try toast rather than bread as everyone digests toast easier. If you must have milk, try A2 milk. Nightshades can cause inflammation, but in my case these affect my skin not my colon. Any foods can be inflammatory if you can't digest them properly and this includes constipating foods like refined flour. Investigate Leaky Gut and Celiac Disease as these diets are anti-inflammatory. If your IBS type leans more to diarrhea this is another clue that you are eating inflammatory foods. RAST tests are good indicators of actual food allergies but the wheat test only tests for certain proteins so an exclusion diet is still the best option.